NE Dory Flotation Location

Builder's Forum
1

I know there have been dozens of threads on the topic of flotation in NE Dorys but I would like to hear your ideas on where additional flotation should be located, assuming you have already done the flotation under all the thwarts per CLC design.  Also, I have seen all the methods that Neil Calore used but I'm hoping to add flotation something short of expedition methods but I'm wanting a capsized dory to come up as dry as possible after rolling into it from deep water.  

Example:

Pool noodles on the rails:
In a capsize the underwater noodle would help the hull ride a little higher but the second the rail comes out of the water, it provides no additional flotation during bailing.

Forward area under a new deck plate, maybe 6" off deck:
I'm thinking this would help both when on its side as well as once righted before bailing

Ideas?

Curt

2

I’ve been chewing on it for a while and plan to work on it this winter. Since the Dory is shaped like a white water canoe - *at the waterline* - I'll fall back on decades of white water canoeing experience. I’m going to rob an airbag like this from one of my WW boats…


http://www.nrs.com/product/42089%20S/nrs-canoe-3-d-short-solo-float

Everyone else probably gets this but it took me a long time to realize the real function of this extra flotation is to Displace water. To that end the bag has to be quite secure. I’ll glue in pad eyes down low, two on each side spaced fore and aft to fit the bag’s dimensions. Additional pad eyes get glued in higher up the sides for laces on top of the bag. This should hold the bag down to the floor. Additional attach points will be affixed to the eye bolt studs and mast step. These will hold a length of 1” webbing to keep the bag from popping out aft when swamped - it’s really no fun when your flotation pops out. Not that I have any experience with that. Nope, none.
To get an idea of how the lashing works have a look at this site - (the prices are stupid but they know how to secure a bag)…


http://www.falllinecanoes.com/air-bags.html


Now what to do with the anchor?


Ok, that’s the bow, the stern is tougher because of all the activity going on back there. I haven’t sussed it out yet. Will probably get the bow bag in and see if it makes the stern sink. If the boat doesn’t float bow high I might not add extra stern floatation but my gut tells me that’s a long shot. My first instinct is to lash down a pair of Beach Rollers at each chine at the stern. Rugged covers and double uses. But, these are too long perhaps…


http://duckworksbbs.com/gear/beachroller/index.htm


Maybe just one, slightly under inflated and curled into a forward facing U?
I’ve fixated on bow and stern bags, partly because they are easy to remove and replace, seem less in the way when installed but also partly because that’s the way we did it in canoes. Looking forward to your more elegant solution Curt.
ev

 

   

3

   

 ev,

 Well from multiple people's comments we may get an elegant solution!  I like the idea of beach rollers too..I've wanted some anyway so why not double them as flotation like you say.   Would need to be quick to remove to use for shore landings.  I like your idea of partially inflating them to make a U shape and maybe I could do that aft of the forward thwart around the DB trunk with the ends pointed aft because I rarely have feet in that area but aft of the DB thwart is an active area for me either rowing or sailing plus when sailing I like to put my leeward foot on the first panel and push on it like pushing on a motorcycle handlebar so putting the rollers in those sections along the chine would be in the way (for me at least), but a roller aft of the forward thwart, another roller forward of the stern seat and a floorboard in the bow seems logical and keeps the flotation low. I like your idea that flotation displaces water, so shouldnt flotation be put low in the boat where water is when righted after a capsize like along the chine, like you say?

BOW:

Your idea is something like this eh?

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjlpcClsoDKAhVVzWMKHdxvC4QQjRwIBw&url=http%3A%2F%2Fwatertribe.org%2Fforums%2Ftopic%2F17-clc-northeaster-dory-for-sale&psig=AFQjCNEHGJgXIWJfcKFYmbYeFLj6ReEndQ&ust=1451455246810546

Now you have me thinking that an airbag like that is a LOT of flotation and my idea of a floorboard in the bow area should be higher than just the top of the mast step, maybe 10" off the bottom with foam underneath it would still allow room for ropes and anchor etc on top of the floorboard instead of an air bag in the bow like the picture...

 

STERN:

Were you thinking of putting an air bag on the stern seat?  Due to passenger possibilities I cant do that but I could put something along the chines in front of the stern seat would work for me like the U-shaped roller with the ends pointed forward.

 

I also thought of using a bunch of Taylor fenders but have since decided I dont like that idea

????

4

I think I might try some 4" PVC pipe sealed at both ends. Maybe three pieces -- 30", 30", and 24". I'd paint these black to match my under-thwart flotation and attach them as low as possible on the aft side below each thwart. (The short one at the bow.) These would provide some flotation, but their equally important function would be to serve as beach rollers for the very rocky beaches on the shores of Norfork Lake.

5

PVC pipe sucks as a beach roller. It's heavy for it's size and cracks and deforms easily when squeezed between a heavy boat and a rock. I use a piece of PVC pipe to cover the rear ladder rack on my truck to protect the bottoms of my boats, but that's fixed in place, doesn't roll and is non-structural.

As far as the flotation bags and inflatable rollers, you guys can't go wrong duplicating this pattern:

Have fun,

Laszlo

 

6

   Indeed, you're right. The Southwester is a boat to dream of for good flotation in all conditions. In fact, I have been reading Webb Chiles books about his attempt at solo sailing around the world in a Drascombe Lugger, an 18-foot Dory much like the Southwester, and have been imagining what that must have been like.

As to the PVC, I admit it wouldn't help much in terms of flotation, but it would make good rollers for my purposes. As you probably know, you can get the pipe in virtually any thickness you want. The thin-walled stuff is easily deformed, but the thicker stuff will really take a beating. Three sections of it would be a bit like three logs that I could easily drag my boat over to get it out of the water (and away from the damage from passing wave-machines). I'll probably craft my "rollers" so that they can't roll -- with a 90-degree bend at each end.

The shores of Lake Norfork are mostly sharp dolostone (like limestone) with plenty of razor-sharp chert. Inflatable rollers wouldn't hold up well and anchors might be hard to set in the rock and impossible to raise if well-set. After 25 years of kayaking, sailing, and rowing around the lake, I can tell you that it is nothing like the ocean -- or even the glacial lakes of the northwoods. The stones are sharp! . . . But the lake is absolutely gorgeous.

7

Now you have me thinking Curt.

Bow: Bingo! Neil is on top of things. A Fastex buckle on the webbing would be a time saver here. I lean to airbags to cut down on weight. I worry about having too much swing weight at the ends. Some one will scream about punctures = 0 flotation. I’ll risk it.

Stern: My post was getting too long, but yes, roller just in front of stern seat on floor - open end of U pointing forward. Seems least in the way here. I think 4-5 straps of 1” webbing through pad eyes with Fastex buckles would fit the bill for ease of removal and be plenty of hold down power. No air bag on seat like Neil’s though. We both need the extra seat.


Hum, maybe the beach roller would work curled up in the bow section too. Less total displacement but probably enough to make a difference. The covering is very rugged to asswage puncture nerves. Webbing, QR buckles, and Bob’s your uncle.
I’ll probably make some low profile pad eyes out of hardwood. But I have seen some pretty slick carbon fiber jobbies in various places.


And what - you steer motorcycles with your feet?!

8

   

I am a HUGE fan of the cross thwarts on the NE Dory because you face forward and slide your butt left or right a little to balance within a tack and slide a little more to the other side to adjust to a new tack. Thus I want the center thwarts, and the floor area between them totally clear from rail to rail with nothing on the floor in that section.

The side seats like on the SW Dory are more like a day sailor, perhaps requiring the sailor to sit sideways facing the center of the boat I would guess?  Anyway, the SW Dory utilizes side seats/air tanks and that isnt an option for me in any position of the NE Dory.

 

Never did learn how to steer a motorcycle with my feet, but the idea of pushing on the handlebar to turn a bike is not unlike the idea of pushing off your leeward foot on the first panel above the floor to balance the boat.

If the logic is correct that additional flotation needs to be placed where water is after the capsized boat is righted, (that is right eh?) then I think I have a plan, largely from the ideas in the posts above:

================================================

1) Boat roller on the chine/floor in a U-shape against the front of the stern seat, with the ends of the U facing forward.

2) Boat roller on the floor in a U-shape against the back of the forward thwart, with the ends of the U facing aft around the DB trunk.

3) A sturdy floorboard in the bow half way up to the rail from the bottom. Shaped to touch each side, aft edge about 2" forward of mast. Strong enough to stand on it, removable if needed, not air tight, and loaded with a stack of pink foam sheets, each one cut to the shape at that point. The floorboard could be made out of Okume or boards to match the rear seat.

Thoughts?

Curt

9

   To wrap this up,....John H, would appreciate your comments too.

Is the logic correct that additional flotation needs to be placed where water is located after the capsized boat is righted, down low?

I watched this video again a bunch of times to see when the water flows into the boat:

https://youtu.be/cCwRUwG7JbI

It's clear in to get your body back into the boat, the rail you are going over will need to be underwater at about the thickness of your body so that you are basically swimming into the boat.  (Agreed??)

SO...the important question...assuming a fair amount of added flotation on the bottom/chine of the boat like described above...  after getting back into the capsized boat:

1) will the dory rails sit higher above the water than they would have without the added flotation?

--or--

2) Will the boat sit at the same level above the water, but result in less water to bail?

 

Thanks!

Curt 

 

10

The glib answer to most questions about enhancing the Northeaster Dory's reserve flotation is "Southwester Dory."  

Seriously, the Northeaster Dory is basically a bone-standard round-sided dory right out of the history books.  None of those had ANY flotation aside from their woodiness, and by that standard the Northeaster Dory is practically a lifeboat.  Certainly for casual usage the under-seat foam is ample and on at least two occasions we've been able to self-rescue our demo model following a capsize in deep water.

Compared to racing dinghies with a lot of decking and sealed tanks, a swamped Northeaster Dory can hold a lot of water.  Were I to set out on any lengthy unsupported trip, I'd stow my gear in dry-bags and lash the bags low in the hull.

Besides being cold and wet, you have two major concerns in the aftermath of a swamping:  the quantity of water to be evacuated, and the loss of stability resulting from the water swilling around inside the boat.

If the latter is your primary concern, putting your flotation up high is the best strategy.  I've seen this done in Northeaster Dories;  here's an example:

Between the foam beneath the thwarts and the flotation arrayed around the perimeter of the hull, this boat would be as stable as a floating dock if swamped.  It would sit low, however, as the flotation up high won't do any floating until there's a lot of water aboard!  You'd have a heap-load of bailing to do but at least you'd have a stable platform for it.

Placing the flotation down low displaces water that's come aboard, and starts working immediately.  Buoyancy down low doesn't do as much for flooded stability, but you're going to have a whole lot less flooding to begin with, so this is the option I would choose.  And in fact the Northeaster Dories that have featured in various stormy WaterTribe events were outfitted this way.  (Click to embiggen.)

I would use a bunch of these carbon eyestraps, epoxied to the sides and bottom of the hull, to take the lashings for my dry-bags.

With the dry-bags distributed as shown in the drawing, the boat will float high and stable following a mishap.  And as the saying goes, the best pump in the world is a scared sailor with a bucket.  Just don't forget your bucket.

 

11

   Wow, great details, John, thanks much.   Funny thing is I had a good discussion today with an employee at the Texas Maritime Museum in Rockport TX about flotation in small boats in general...he said the exact same thing you did about flotation only on the bottom of the boat can make a swamped boat tippy.  Come to think of it, the 9' hydroplane I built years ago had flotation only under the floorboard and when flipped, the boat floated upside down!    Since I dont do overnight sails I dont think I'll get dry bags, or even kayak air bags, but I do want some flotation low, and some high, so my current thought is simple....buy two yellow inflatable boat rollers, drape them over the outside ends of the middle thwart and bend the ends down to tie the ends to  carbon eyestraps on the floor at the chine, all with webbing clips so they can be unsnapped for use as beach rollers.  I may still do a floorboard in the bow with pink foam too.

Now if I could stay home long enough to work on the boat!

 

Thanks all..Curt